Flight plans and red plugin symbol

Hi, Have been using Abacus Copilot for a while now. However when I go into my documents folder where flights are saved also, there is a red plugin symbol. When I click on any of the flights, I get a message saying windows cannot open this program. Windows needs to know what program created it. I was trying to create a flight in Europe but it would'nt show up in copilot. Now I know why because of this plugin problem. Anybody know what this could mean? I'm at a lost. Never seen this before. Thank you.